Figure 4. Transmission progress of new block
Figure 4 illustrates the schematic diagram of the propagation process of a new block in blockchain network. After running PoW consensus algorithm for some time, Server A first finds a ”valid” new block and attempts to propagate new block information to all nodes through blockchain network. Server A first needs to send the new block information to adjacent node B, and then Server B sends such information to other adjacent nodes. Such process would be repeated until all nodes in blockchain network receive the new block information. By analyzing this process, it can be seen that the generation and propagation of new block have following characteristics:
(1) Low Efficiency in Generating New Blocks. During block generation process, all computing resources in blockchain network are used to find a ”valid” new block. As of June 2023, the total computational power of Bitcoin network has exceeded 370EH/s. It is evident that to achieve decentralization, PoW algorithm has sacrificed computing efficiency to some extent[10].
(2) Long Time to Generate New Blocks. During block generation process, if no node in blockchain network finds a ”valid” new block, all nodes must continue running PoW algorithm. The average time to generate a new block is regulated by block generation target value, and to ensure system stability, this time cannot be set too small. For Bitcoin system, the average time to generate a new block is about 10 minutes[11]. Block generation speed limitation restricts the promotion and application of blockchain in some fields.
(3) Size Limitation for Individual Blocks. To ensure efficient propagation of the new block in blockchain network, the size of an individual block cannot be too large; otherwise, it would significantly prolong the time for entire network to reach consensus. In Bitcoin system, each block must not exceed 1MB[11]. Thus, the upload bandwidth of blockchain data is also limited.
In response to above problems, many new consensus algorithms have been proposed in recent years, such as Proof of Stake (PoS)[12], Delegated Proof-of-Stake (DPoS)[13], Proof of Space [14], Proof of Elapsed Time [15], etc. These algorithms replace the computing power competition in PoW with different competition methods to address resource consumption and security issues. However, these algorithms have not yet been experienced large-scale, long-term practical testing and have reduced the decentralization capability and usability of blockchain.
3. Characteristics of electric power data transmission
Power grid, as a vast electromechanical hybrid system, suffers from the risk of failure spreading throughout network, threatening the stability of entire system. To ensure the safe and stable operation of power grid, the timely transmission of grid status information to dispatch control center through electric power data network is of great significance. However, with the trend of power grid digitization development, electric power data transmission faces risks such as network attacks and malicious tampering. How to enhance the reliability of electric power data transmission and verify data credibility has become a key focus of academia and industry[16-19]. Blockchain as a cutting-edge technology can effectively build a trustworthy data transmission environment, becoming one of the alternative solutions to above problems.
Currently, electric power data is mainly carried in dedicated data networks. Unlike traditional Internet, the architecture of electric power data network is clear and fixed, and its business characteristics are explicit, allowing further optimization and enhancement of data transmission by applying blockchain techniques.
3.1. Power Dispatch Network Architecture and Transmission Services
Electric power dispatch data network is a dedicated data network for electric power dispatching and production services. Figure 5 shows the schematic diagram of electric power dispatch data network architecture. As can be seen from the figure, the architecture of electric power data network is a tree structure. Substations and power plants, as the terminal nodes in network, transmit operating data to dispatch and control center through dispatch data network via plant and station network equipment. To ensure the reliability of data transmission, each plant and station equipment is configured in a dualized manner, separately connected to two different levels of access networks[20]. Compared to traditional Internet, the main characteristics of electric power dispatch data network architecture are focused on two aspects: first, dispatch data network only carries electric power dispatching services, and its business nature and performance requirements are relatively fixed; second, once dispatch data network is established, there are very few large-scale changes in grid topology structure, and data transmission paths would rarely change.